Previous studies have shown that, for good low-speed skidding resistance of concrete roads, the fine aggregate is the most important constituent of a mix and should have high resistance to abrasion as well as high resistance to polish. This report describes the development of a polishing test that measures a combination of these essential properties. The test procedure, carried out on a mortar made from the fine aggregate, has been developed by adapting the apparatus and the procedure used for the determination of the PSV of coarse aggregate. Alterations to the PSV test have been kept to a minimum; they mainly concern specimen manufacture, the rubber tyre and the applied load. Results from this new test, known as the polished-mortar value (PMV) test, have been obtained on a range of fine aggregates and found to correlate well with the skid-resistance values of road concretes containing these same fine aggregates. A multiple correlation analysis showed that the PMV adequately describes the major material factors influencing the low-speed skidding resistance of concrete surfaces under site conditions. Secondary factors that were also significantly correlated with road performance were fine-aggregate content and, on a very heavily trafficked road, the PSV of the coarse aggregate. This new test method offers a possible alternative to the accelerated wear test for the specification of aggregates for concrete roads. (Author/publisher)
Samenvatting